The Forebrain Plasticity in l-lypertenslon Program is a new multidisciplinary research program focused on the fundamental biological processes governing the neurohumoral interaction between key forebrain centers and the cardiovascular system. The long-term objective of the program is to elucidate the role of these centers in the pathogenesis of hypertension and in the ensuing end-organ damage, particularly cerebrovascular damage. The central theme of the PPG focuses on the role of the subfornical organ (SFO), one of the circumventricular organs, and the hypothalamic paraventricular nucleus (PVN), the main output pathway of the SFO, in the sympathetic overactivity and hormonal release underlying the increase in blood pressure. The central hypothesis is that in slow-developing hypertension there are adaptive modifications (neuroplasticity) in the SFO-PVN axis that turn maladaptive, and set the stage for the neurohumoral dysregulation driving the hypertension and the cerebrovascular dysfunction. Each project addresses a specific facet of the central hypothesis using a clinically relevant mouse model of hypertension produced by systemic infusion of a low dose of angiotensin II (Angll). Project 1 will examine the downstream signaling mechanisms in SFO by which Angll induces the hypertension, focusing on the role of prostanoids as essential intermediaries. Project 2 will examine critical structural and functional maladaptive mechanisms in the PVN, which enable the neurohumoral dysfunction underlying the development of hypertension. Project 3 will focus on the structural and functional modifications in the PVN that are responsible for the increased susceptibility to hypertension in menopausal females. Project 4 will address the role of the SFO-PVN axis in the deleterious effects of hypertension on vital cerebrovascular regulatory mechanisms that assure an adequate blood flow delivery to the brain. The Projects are supported by an Administrative Core, a Molecular Biology-Mouse Core, a Neuroanatomv-lmaaina Core and a Radiotelemetrv Core. A major strength of the program is that each project combines molecular, neuroanatomical, neurophysiological and cardiovascular integrative approaches to achieve the stated goals. The projects are led by a highly interactive group of established investigators and build on each other's strengths so that the scientific output of one project interacts synergistically with the research proposed in other projects. Thus, the collective scientific outcome of the Program is anticipated to be greater than the sum of its individual components.